Fuel cell systems with maintenance hydration

Abstract

Fuel cell systems, and more particularly to fuel cell systems with fuel cell hydration provided during periods of inactivity by combining a fuel and an oxidant. In some embodiments, the systems may include at least one fuel cell with an anode region and a cathode region. The at least one fuel cell may be hydrated by disposing both a fuel and an oxidant in the anode region, the cathode region, or both the anode region and the cathode region, and, optionally, without generation of electrical output. In some embodiments, the systems may include a controller that controls combined delivery of a fuel and an oxidant to the at least one fuel cell. In some embodiments, the systems may deliver a mixture of the fuel and the oxidant to the at least one fuel cell after a period of fuel cell inactivity.

1 . A fuel cell system with maintenance hydration during periods of inactivity, the fuel cell system comprising:
 at least one fuel cell including an anode region, a cathode region, and an electrolytic barrier that permits selective movement of positive charge between the anode region and the cathode region;   a reactant delivery system for directing a fuel and an oxidant to the at least one fuel cell, the reactant delivery system including a conduit assembly having (1) a first configuration that directs the fuel to the anode region and the oxidant to the cathode region for generation of electrical output, and (2) a second configuration that directs both the fuel and the oxidant to the anode region, to the cathode region, or both to the anode region and to the cathode region, to generate water; and   a controller operatively coupled to the reactant delivery system and adapted to control configuring of the conduit assembly into the second configuration such that the at least one fuel cell is hydrated without generation of electrical output.   
     
     
         2 . The fuel cell system of  claim 1 , wherein the reactant delivery system includes a valve that selects whether the fuel is directed to the anode region or the cathode region, and wherein the controller controls operation of the valve. 
     
     
         3 . The fuel cell system of  claim 1 , wherein the controller is configured to control configuring of the conduit assembly into the second configuration based at least in part on at least one measured characteristic of the fuel cell system, of the environment near the fuel cell system, or of both, and wherein the at least one measured characteristic corresponds to temperature, humidity, hydration, or a combination thereof. 
     
     
         4 . The fuel cell system of  claim 1 , further comprising a timer mechanism in communication with the controller, wherein the controller is configured to control configuring of the conduit assembly into and/or out of the second configuration at least in part according to one or more time values measured by the timer mechanism. 
     
     
         5 . The fuel cell system of  claim 1 , further comprising a hydration sensor in communication with the controller, the controller being configured to control configuring of the conduit assembly into and/or out of the second configuration at least in part according to a level of hydration measured by the hydration sensor. 
     
     
         6 . The fuel cell system of  claim 5 , wherein the hydration sensor measures an impedance of the at least one fuel cell. 
     
     
         7 . The fuel cell system of  claim 1 , further comprising a sensor that measures an ambient condition, the sensor being in communication with the controller such that the controller controls configuring of the conduit assembly into and/or out of the second configuration based, at least in part, on the ambient condition measured by the sensor. 
     
     
         8 . The fuel cell system of  claim 1 , wherein the controller is configured to control automatic configuring of the conduit assembly into the second configuration responsive to at least a predetermined time period elapsed since the at least one fuel cell was in the first or the second configuration. 
     
     
         9 . The fuel cell system of  claim 1 , wherein the first and second configurations provide distinct rates of flow of the fuel to the at least one fuel cell, and wherein the rate of flow with the second configuration is substantially less than the rate of flow with the first configuration. 
     
     
         10 . The fuel cell system of  claim 1 , further comprising a drive mechanism that propels the oxidant along the conduit assembly, wherein the drive mechanism is in communication with the controller such that the controller controls operation of the drive mechanism to provide distinct rates of oxidant flow when the conduit assembly is in the first and second configurations. 
     
     
         11 . The fuel cell system of  claim 1 , wherein the at least one fuel cell is a hydrogen fuel cell that generates electrical output by converting hydrogen and oxygen to water. 
     
     
         12 . The fuel cell system of  claim 1 , further comprising a stack of fuel cells including the at least one fuel cell. 
     
     
         13 . A method of hydrating a fuel cell system including at least one fuel cell having an anode region, a cathode region, and an electrolytic barrier that permits selective movement of positive charge between the anode region and the cathode region for generation of electrical output, the method comprising:
 delivering both a fuel and an oxidant to the anode region, the cathode region, or both to the anode region and to the cathode region, such that the fuel and the oxidant are in contact with each other and react to increase hydration of the at least one fuel cell without generating electrical output.   
     
     
         14 . The method of  claim 13 , wherein the step of delivering includes a step of delivering a predefined ratio of a fuel and an oxidant. 
     
     
         15 . The method of  claim 13 , wherein the fuel is hydrogen, and wherein the electrolytic barrier is a proton exchange membrane. 
     
     
         16 . The method of  claim 13 , further comprising a step of combining the fuel and the oxidant before the step of delivering. 
     
     
         17 . The method of  claim 16 , wherein the step of combining includes a step of combining the fuel and the oxidant at less than the lower flammability limit (LFL) of the fuel. 
     
     
         18 . The method of  claim 13 , further comprising a step of generating electrical output by supplying the fuel to the anode region and the oxidant to the cathode region such that the fuel and the oxidant are separated from each other by the electrolytic barrier. 
     
     
         19 . The method of  claim 13 , wherein the step of delivering is performed after a period of inactivity during which the at least one fuel cell did not generate electrical output. 
     
     
         20 . The method of  claim 19 , further comprising a step of selecting a time for starting the step of delivering based at least in part on a predefined period of inactivity for the at least one fuel cell. 
     
     
         21 . The method of  claim 13 , wherein the step of delivering is performed periodically. 
     
     
         22 . The method of  claim 13 , further comprising a step of measuring a characteristic corresponding to a level of hydration of the fuel cell system, and a step of selecting a time for starting the step of delivering based at least in part on the measured characteristic. 
     
     
         23 . The method of  claim 13 , further comprising a step of measuring ambient temperature or ambient humidity, and a step of selecting a time for starting the step of delivering based at least in part on the ambient temperature or ambient humidity measured. 
     
     
         24 . The method of  claim 23 , wherein the step of selecting a time includes a step of selecting a time for which the ambient temperature is below a predefined threshold temperature. 
     
     
         25 . The method of  claim 13 , wherein the step of delivering is started automatically. 
     
     
         26 . The method of  claim 13 , further comprising a step of supplying a fuel to the anode region and an oxidant to the cathode region for generation of electrical output. 
     
     
         27 . The method of  claim 26 , wherein the fuel has a flow rate, and wherein the flow rate for the step of delivering is substantially less than the flow rate for the step of supplying. 
     
     
         28 . The method of  claim 26 , wherein the oxidant has a flow rate, and wherein the flow rate for the step of delivering is different than the flow rate for the step of supplying. 
     
     
         29 . A method of operating a fuel cell system having at least one fuel cell with an anode region, a cathode region, and an electrolytic barrier that permits selective movement of positive charge between the anode region and the cathode region for generation of electrical output, the method comprising:
 generating electrical output by disposing a fuel in the anode region and an oxidant in the cathode region; and   hydrating the at least one fuel cell by (1) mixing the fuel and the oxidant to form a mixture, and (2) disposing the mixture in the cathode region, in the anode region, or both in the cathode region and in the anode region, to produce water.   
     
     
         30 . The method of  claim 29 , wherein the step of hydrating is performed after a period of inactivity during which the step of generating was not performed. 
     
     
         31 . The method of  claim 30 , wherein the step of hydrating is performed after a predefined period of inactivity has elapsed. 
     
     
         32 . The method of  claim 29 , wherein the step of hydrating is started automatically. 
     
     
         33 . The method of  claim 29 , wherein the step of hydrating does not generate electrical output.